Transparent conductive oxides (TCOs), such as doped zinc oxide, indium tin oxide (ITO) and indium molybdenum oxide are widely used as conductive optically transparent electrodes. These oxides exhibit both high electrical conductivity and optical transparency, in the visible spectrum. However, all of these oxides are characterized as n-type materials and their use is accordingly limited. In order to expand the use of TCOs to applications such as solar cells, transparent transistors, transparent light emitting diodes (LEDs), ultraviolet (UV) detectors, etc. there is a need for optically transparent conductive p-type materials which are compatible with the existing n-type TCOs. There is also a need for transparent p-type semiconductor materials that can be incorporated in devices with low cost substrates that may limit process temperatures. Furthermore, there is a need for methods and apparatuses for forming these materials.
In recent years, dye-sensitized solar cells (DSSCs) have received considerable attention as a cost-effective alternative to conventional solar cells. DSSCs operate on a process that is similar in many respects to photosynthesis, the process by which green plants generate chemical energy from sunlight. Central to these cells is a thick semiconductor nanoparticle film (electrode) that provides a large surface area for the adsorption of light harvesting organic dye molecules. Dye molecules absorb light in the visible region of the electromagnetic spectrum and then “inject” electrons into a nanostructured semiconductor electrode. This process is accompanied by a charge transfer to the dye from an electron donor mediator supplied by an electrolyte, resetting the cycle. DSSCs based on liquid electrolytes have reached efficiencies as high as 11% under AM 1.5 (1000 W m−2) solar illumination. However, a major problem with these DSSCs is the evaporation and possible leakage of the liquid electrolyte from the cell. This limits the stability of these cells and also poses a serious problem in the scaling up of DSSC technology for practical applications.
Presently, tremendous efforts are being focused on fabricating solid state DSSCs (SS-DSSCs) by replacing liquid electrolytes with solid electrolytes such as molten salts, organic hole transport materials, and polymer electrolytes. However, most of the SS-DSSCs suffer from the problems of short-circuit and mass transport limitations of the ions, and so have low conversion efficiencies compared with the liquid version. There is a need for: solid electrolyte materials for making stable, high efficiency SS-DSSCs; process tools for making said solid electrolyte materials; new designs of SS-DSSCs comprising said solid electrolyte materials; and manufacturable methods of making said materials and said SS-DSSCs.